Nozzle construction for turbines



2 Sheets-sheet 1 IN1/Enron /ws Mouw/Pr# mom/frs July 3, 1934. H.HOLZWARTH NOZZLE CONSTRUCTION -FORTURBINES Filed April 2s, i927 UWIT/V588 y WMM/M July 3, 1934. H. HoLzwARTH NOZZLE CONSTRUCTION FORTURBINES Filed April 23, 1927 2 Sheets-Sheet 2 A TTOHNEYS Patented July3, 1934 UNITED STATES Nozzm ooNs'rnUc'rIoN ron 'ruminvrzsV ,l

' Hans Holzwarth, Dusseldorf, Germany, assignor to Holzwarth Gas TurbineCo., San Francisco, Calif., a corporation of Delaware Application Aprilk23, 1927, Serial No. 186,095

3 Claims. (Cl. (S0-4 1) In turbines using combustion gases, according toconstructions of a type developed by me, it has been the practiceheretofore to pass the combustion gases from the valved outlet of acombustion chamber to an intermediate chamber or conduit and from thelatter to a plurality of nozzles discharging a plurality of jets fromsuch chamber against the blades of the turbine rotor. These nozzles wereseparated by partitions, the latter cooled or uncooled. The walls ofthis interme- 'diate chamber were cooled, as by means of a water jacket,and it was found that the amount of heat thus abstracted fromthe-'combustion gases was quite considerable, and that the veiiiciencyof the turbine was materially reduced thereby.

In view of this difliculty, it has been my aim to reduce the transfer ofheat from the combustion gases on their way from the combustion chamberto the nozzles, and my present invention relates to a very simple andefficient type of con'- struction for accomplishing this' result. Afea.- ture of my invention consists in the substitution for theplurality of nozzles, which in prior constructions have been connectedwith each intermediate chamber or channel, of a single nozzle forconducting to the turbine rotor all of the combustion gases generated ina combustion chamber,

l the said nozzle converging from its inlet to a point of minimumcross-section only slightly removed from said inlet, and increasing incrosssectional area from such point to a point near the outlet end ofthe nozzle, the outlet end itself being fitted in segment-like fashionto the rotor circumference. This arrangement reduces the size of theintermediate channel between the outlet valve located at the mouth ofthe combustion chamber and the nozzle itself, that is, the narrowestsection of the latter, to the smallest possible magnitude with acorresponding decrease in the amount of heat lost by the combustiongases before they reach such narrowest section of the nozzle. Anotherfeature of my present invention relates to the shape of the chamber orconduit through which the gases pass from the outlet valve of thecombustion chamber tothe nozzle proper. According to my invention, thischamber or conduit is made as small as possible, and is contracted afterthe fashion of a funnel converging toward the narrowest portion of thenozzle. I ,prefer to make the walls of this intermediate chamber orconduit follow straight lines from the immediate vicinity of the nozzleor exhaust valve of the explosion chamber to the inlet end of thenozzle, the volume of such conduit being thereby made a minimumconsistent with the absence of throttling. Due to such construction, thegas ,pressure builds up more rapidly in the nozzle conduit or channel tothat prevailing in the explosion chamber, and with a lower drop inpressure from themaximum explosion pressure, than in the larger nozzleconduits heretofore employed. In this manner I minimize the expansionand whirling motion of the gases in such tapering or funnel-shapedportions, and this again reduces the losses due to abstraction of heat,investigations having shown that such whirling motion is responsible fora considerable proportion of the heat losses occurring between thecombustion chambers and the nozzles, in constructions prior to mypresent invention.

. I am aware that my United States Patents Nos. 853,925 and 877,194 showconstructions in which a single nozzle is associated with eachcombustion chamber. In both of these patents, however, the nozzleconduits are large, as were the conduits in a number of explosionturbines built by me subsequently to these patents, in which turbinesthe heat losses in the nozzle conduits were enormous; these patents,moreover, fail'to show other constructional features describedhereinbelow and defined in the claims.

Without desiring to restrict myself to the particular detailsillustrated, I will now describe a preferred and satisfactory embodimentof my present invention, with reference to the accompanying drawings, inwhich Fig. 1 is a partial longitudinal section through a turbineprovided with my improved nozzle and nozzle conduit; Fig. 1a is ahorizontal section or a reduced scale taken through the conduit andvalve shown in Fig. 1; Fig. Z'is a section along the axis of the nozzle,substantially on line 2-2 of Fig. 1; and Fig. 3 is a face view, lookinglengthwise ofthe turbine shaft, against the outlets of the nozzles, withparts omitted.

The apparatus shown comprises a plurality of combustion chambers 10provided with suitable devices for the admission of air and fuel and forthe ignition of the combustible mixture. As these devices form nofeature of my present invention, and may be of any well-known orapproved construction, I have not shown or described them in detail inthe present application. The combustion gases pass out from the chambers10 into conduits 11, there being one such conduit for each chamber4 10,andthe connection to each conduit is controlled by an outlet valve 12,the several valves being actuated by the turbine in any approved 'manner(not shown). As illustrated by Fig. 1, the conduit 11 vmay be jacketedfor the circulation of water or other cooling medium, and the Jacket maybe extended to cool that -portion of the combustion chamber .10 which isadjacent to its outlet. I The conduit 11 is widest in the neighborhoodof the valve 12, the outletof the explosion chamber being ofconsiderablylarger diameter than the inlet-of the nozzle as shown inFig. 1a. As the walls of the nozzle conduit or channel run along 1osubstantially straight lines from the region of the nozzle valve to theinlet of the nozzle, the cross-section of the conduit 11 constantlydiminishes from the nozzle valve to the nozzle, so that the volume ofsuch conduit is made a minimum 15 without causing throttling ofthegases. There is but a single nozzle for each combustion chamber 10 andits conduit 11, said nozzle being of the De Laval type. The outlets ofsuch nozzles are close to the plane of rotation of the blades 14 2o onthe rotor 15, or of the first set of rotor blades, when (as illustrated)the rotor has more than one set of blades, in which case a set ofstationary bladesr 16 is interposed between the adjoining sets A ofrotor blades. As shown, the explosion chambers are arranged with theirlongitudinal axes parallel to the turbine shaft, whereby a large numberof chambers may be associated with the turbine rotor. As' more clearlyshown in Fig. 3, the outlets of the nozzles are curved in the form ofsegments so as to conform to the arrangement of the rotor blades, and aseach combustion chamber has only one nozzle, each segment-like outlet ismade long enough to discharge the gases against a plurality of bladeswhich it spans.

' The conduit 1l is relatively short, and the narrowest portion orthroat 13 of the nozzle is relatively close to said conduit, the majorportion of the nozzles length lying between said throat 13 and thenozzle outlet. From said throat the noz.- 40 zle passage aresboth towardthe nozzle inlet in funnel-like fashion and toward the nozzle outlet, asindicated at 13a and 13b respectively. The general direction of thenozzle is oblique both when viewed in an axial plane (Fig. 1) and whenlooking along the turbine axis (Fig. 3); that is,

the nozzle inlet is farther away from the turbine axis than the nozzleoutlet, and furthermore, the

inlet and the outlet are in different axial planes,

the outlet being in advance of the inlet, in the direction of therotation. The nozzles 13 may also be jacketed, as indicated at f13, forthe circulation of water or other cooling fluid. A

The nozzle 13 diverges from the constricted section 13 to a pointnearthe outlet end thereof at which the gases have expanded to an extentdetermined by the expansion ratio of the nozzle.

Fromthis point to the outlet end of the nozzle the walls of the nozzleno longer diverge but are parallel to the nozzle axis through thisoutlet section, as shown in Fig. 2.

By adapting the nozzle outlets in segment-like fashion to the rotorcircumference in accordance withA the present invention, wherein thenozzles are so constructed that the walls of the outlet portion thereofrun parallel to the nozzle axis fromthe point at which the necessaryexpansion relation is attained to the nozzle outlet, it is possible to`retain the necessary expansion relation with the smallest possiblecircumferential extent of the nozzle outlet. In this manner a sumcientnumber of nozzle outlets and consequently of combustion chambers maybearranged about the rotor circumference t permit an economical operationof the turbine. In other words, my invention actually makes practicablethe utilizalet, a single De Laval nozzle, and a conduit leadtion of asingle nozzle for each combustion chamber. This single nozzle is of thegreatest importance because it makes possible a reduction by fullyone-third of the heat losses suffered by the gases on their way to therotor.

It will befclear from Figs. 1 and 1a that the walls of the connectingconduit 11 extend along straight lines from the 'outlet of thecombustion chamber to the inlet of the nozzle valve 11. The conduit istherefore free of enlargements and has a minimum volume consistent withthe absence of throttling, so that the pressure in such conduit, uponopening of the nozzle valve 12, Y rapidly builds up and becomes equal tothat prevailing in the explosion chamber after only a very short dropfrom the maximumA explosionpressure of the gases.

For the reasons explained in the introductory part of thisspecification, an arrangement such as described with reference to theaccompanying drawings reduces to afsvery considerable extent the lossesdue to abstraction of heat from the .combustion gases on their way fromthe valvecontrolled outlets of the combustion chambers 10 to the throatsor narrowest portions of the 100 nozzles, such throats 13' being muchnearer to the outlet valves 12 than in previous constructions, and thearea of heat-abstracting surfaces being much smaller. Another reason forthe reduction of the heat losses is found in the funnel shape of theconduit 11 and of the nozzle portion 13, whereby whirling motion of thegases is minimized. The eciency of the turbine is inwhich not only isrelatively short, as stated above, 1 5

but includes no enlargements and is throughout asnearly equal aspossible in cross-sectional area tothe minimum necessary to convey allthe gases to the nozzle within the small period of time allowed by eachexplosion cycle.

Various modifications may be-made without departing from the nature ofmy invention as set forth in the appended claims;

I claim:

1. In an apparatus for driving turbines by means of combustion gasesunder pressure, a turbine rotorfan explosion chamber supported with itslongitudinal axis parallel to the shaft of the rotor and having avalve-controlled out- 13o ing from said outlet to the inlet portion ofthe nozzle, the said outlet being of considerably larger cross-sectionthan the inlet of the nozzle, the walls of said conduit extending' alongstraight lines from said outlet'to the inlet of said nozzle anddiminishing in cross-section gradually from such outlet in the nozzleinlet, whereby the vollume of said conduit is kept at a minimum withabsence of throttling, said nozzle being adapted to conduct to the rotorof the turbine all the gases discharged by said combustion chamberthrough said conduit, and being constricted near its upper portion, saidupper portion being directly connected to said conduit and of funnel ushapeand converging from the inlet opening to the constricted section ofsaid nozzle, the nozzle increasing in cross-section from saidconstricted section to a point near the outlet thereof, said latteroutlet being in the form of a segment corresponding to the curvature ofthe Vperiphery of the rotor and spanning a plurality of blades of saidrotor.

2. In an apparatus for driving turbines byV means of combustion gasesunder pressure, a turbine rotor, an explosion chamber supported with itslongitudinal axis parallel to the shaft of the rotor and having avalve-controlled out- Y let, a single De Laval nozzle, and a conduitdening an intermediate channel between said outlet and said nozzle, thesaid outlet being of considerably larger cross-section than the inlet ofthe nozzle, the walls of said conduit extending along straight linesfrom said outlet to the inlet of said nozzle, whereby the volume ot saidconduit is kept at a minimum with absence of throttling, the nozzlebeing adapted to conduct to the rotor of the turbine all of thecombustion gases generated in said chamber and converging from its inletto a point of minimum cross-section adjacent to its inlet and divergingfrom such point to a point near the outlet end thereof, the walls of theouter section of the nozzle from said latter point to the dischargeoutlet being parallel to the axis or the nozzle and fitted in the formof a segment to the r'otor circumference so as to maintain theexpansion.

3. In an apparatus for driving turbines by means of combustion gases,the combination of a turbine rotor, an explosion chamber supported withits longitudinal axis parallel to the shaft of the rotor and having avalve-controlled outlet, a single De Laval nozzle arranged to dischargeagainst said rotor all of the gases generated insaid chamber, and aconduit dening an intermediate channel between said outlet and saidnozzle, the said outlet .being of considerably larger cross-section thanthe inlet of the nozzle, the walls of said conduit extending alongstraight lines from said outlet to the inlet of said nozzle, whereby thevolume of said conduit is kept at a minimum with absence of throttlingand pressure consequently rapidly built up therein upon opening of saidvalve-controlled outlet, so that whirling of the gases and loss of heatin said channel are reduced to a minimum.

HANS HOLZWARTH.

